Patterning methods and systems using reflected interference patterns

ABSTRACT

A method for patterning a layer on a substrate can include projecting coherent radiation toward a reflector surface so that the coherent radiation is reflected off the reflector surface to provide a holographic projection of a desired image wherein the reflector surface includes information that corresponds to an inverse of the holographic projection of the desired image. The substrate including the layer can be maintained in the path of the reflected radiation so that the holographic projection is projected onto the layer. Related systems are also discussed.

RELATED APPLICATIONS

[0001] The present application claims priority from U.S. ProvisionalApplication Ser. No. 60/185,288 filed Feb. 28, 2000, the disclosure ofwhich is hereby incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to the field of microelectronicsand more particularly to microelectronic patterning.

[0003] As integrated circuit devices become more highly integrated,dimensions of structures such as conductive lines and via holes andspaces therebetween are reduced. Accordingly, patterning processes areneeded for smaller patterns. In the past, conventional opticallithography techniques have been used.

[0004] In optical lithography, an image of a pattern is opticallyprojected onto a substrate by transmitting radiation through a maskincluding the pattern thereon. In essence, a pattern from a mask isprojected onto a photosensitive material which is then developed so thatthe developed photosensitive material has the pattern of the mask. Asthe dimensions of microelectronic structures are further reduced,however, mask projection techniques may limit further reductions inpattern sizes.

[0005] Accordingly, there continues to exist a need in the art forimproved patterning methods and systems.

SUMMARY OF THE INVENTION

[0006] According to embodiments of the present invention, a layer on asubstrate can be patterned using interference patterns. For example,coherent radiation can be projected toward a reflector surface so thatthe coherent radiation is reflected off the reflector surface to providea holographic projection of a desired image wherein the reflectorsurface includes information that corresponds to an inverse of theholographic projection of the desired image. The substrate including thelayer can be maintained in the path of the reflected radiation so thatthe interference pattern is projected onto the layer. Accordingly, theholographic projection of the desired image can be used to patter thelayer. For example, after maintaining the substrate including the layerin the path of the reflected radiation, the layer can be developed sothat portions thereof are maintained and removed according to theintensity of the holographic projection of the desired image projectedthereon.

[0007] Methods and systems according to embodiments of the presentinvention can thus provide patterning for microelectronic structureshaving relatively fine dimensions. Moreover, defect tolerance can beincreased because the effect of a defect on the reflector surface isdistributed throughout the interference pattern projected onto thesurface of the layer being patterned.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 is a block diagram of a reflective holographic microscope.

[0009]FIG. 2A is a cross-sectional view of a sphere on a siliconsubstrate subjected to coherent radiation.

[0010]FIG. 2B is a hologram computed using the coherent radiation ofFIG. 2A.

[0011]FIG. 3A is a cross-sectional view of two spheres on a siliconsubstrate subjected to coherent radiation.

[0012]FIG. 3B is a hologram computed using the coherent radiation ofFIG. 3A.

[0013]FIG. 4A is a cross-sectional view of one sphere on a second sphereon a silicon substrate subjected to coherent radiation.

[0014]FIG. 4B is a hologram computed using the coherent radiation ofFIG. 4A.

[0015]FIG. 5A is a cross-sectional view of a cube on a silicon substratesubjected to coherent radiation.

[0016]FIG. 5B is a hologram computed using the coherent radiation ofFIG. 5A.

[0017]FIG. 6 is a block diagram of a reflective holographic microscopeincluding a laser.

[0018]FIG. 7 is a reconstructed image generated using off-axisholography.

[0019]FIG. 8 is a block diagram of a patterning system.

[0020]FIG. 9 is a cross sectional view of a reflector including aplurality of topographical features.

[0021]FIG. 10 is a block diagram of a patterning system including aplurality of radiation sources.

[0022]FIG. 11 is a block diagram of a patterning system including aplurality of patterning reflectors and a plurality of reflectors.

[0023]FIG. 12 is a block diagram of a patterning system including afilter.

DETAILED DESCRIPTION

[0024] The present invention will now be described more fullyhereinafter with reference to the accompanying drawings, in whichpreferred embodiments of the invention are shown. This invention may,however, be embodied in many different forms and should not be construedas limited to the embodiments set forth herein; rather, theseembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the invention to thoseskilled in the art. Like numbers refer to like elements throughout.

[0025] It will be understood that when an element such as a layer,region, or substrate is referred to as being “on” another element, itcan be directly on the other element or intervening elements may also bepresent. In contrast, when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present. In the drawings, the dimensions of layersand regions are exaggerated for clarity.

[0026] A block diagram illustrating a reflective holographic microscope31 and methods used to characterize a sample surface 41 is shown inFIG. 1. As shown, the microscope can include a source of coherentradiation 33, a detector 35, a controller 37, and an output device 39.The radiation source 33 projects coherent radiation 34 along divergentpaths toward the sample surface 41 so that the coherent radiation isreflected or scattered off the sample surface 41. The detector 35defines an interference plane 36 to detect an interference patterngenerated by the reflected and unreflected portions of the coherentradiation 34 incident on the interference plane. In particular, thedetector may detect both amplitude and phase information of radiationincident on the interference plane 36 to provide a measurement of aninterferogram or Fresnel hologram resulting from interference of thereflected and unreflected portions of the coherent radiation at theinterference plane. For example, the detector 35 may be a charge coupleddevice (CCD) that generates a digital representation of the radiationincident on the interference plane. Alternately, other detectors knownnow or developed in the future may be used.

[0027] Measurements of the reflected and unreflected portions of thecoherent radiation can then be provided by the detector 35 to thecontroller 37. The controller can use the amplitude and phaseinformation included in these measurements to reconstruct athree-dimensional image of the sample surface 41. The three-dimensionalimage can be displayed on an output device 39 such as a CRT or LCDscreen or a printer. Alternately or in addition, the controller can usethe amplitude and phase information to make measurements of particularfeatures of the sample surface. As shown in FIG. 1, the sample surfacemay include a raised portion 43 such as a gate electrode, a conductiveline, or an isolation region, and it may be desirable to determine awidth of the raised portion 43. The controller can use the amplitude andphase information to determine a width of the raised portion. Inaddition, heights and/or shapes of raised portions can be determined.Alternately or in addition, widths, depths, and/or shapes of trenches orholes can be determined.

[0028] The controller can use geometric calculations based on theamplitude and phase information to reconstruct the three-dimensionalimage of the sample surface. As will be understood by those having skillin the art, the controller can be implemented using special purposehardware-based systems, general purpose computer systems together withcomputer instructions, and/or combinations of special purpose andgeneral purpose systems. As will be further understood, the controllercan be implemented using one or more integrated circuit devices,combinations of discrete circuit devices, and/or combinations ofdiscrete and integrated circuit devices. Moreover, while the detector 35and the controller 37 are illustrated as separate blocks in FIG. 1, itwill be understood that the detector could be implemented as a portionof the controller, or the detector could be implemented as a separateblock including functionality discussed above as being performed by thecontroller. The controller 37 can also be used to maintain relativepositions of the radiation source 33, the sample surface 41, and thedetector 35.

[0029] According to a particular embodiment of the present invention,the radiation source 33 can project a coherent beam of electrons. Forexample, the radiation source 33 can be a field emitter that emits anelectron beam in response to a voltage applied thereto. In particular,the radiation source can be a nanotip field emitter wherein the tip hasdimensions on the order of an atom. By providing a nanotip with thesedimensions, a coherent electron beam can be generated by applying avoltage difference between the radiation source and the sample surface41.

[0030] The preparation of a single-atom tip from W [111]-oriented singlecrystal wires is discussed, for example, in the reference by Hans-WernerFink et al. entitled State Of The Art Of Low-Energy Electron Holography,Electron Holography, A. Tonomura et al. (Editors), Elsevier Science B.V., 1995. The Fink et al. reference also discusses the generation of abeam of coherent electrons using the single-atom tip. The Fink et al.reference is hereby incorporated herein in its entirety by reference.The voltage difference between the radiation source 33 and the samplesurface 41 can be generated using the controller 37 as shown in FIG. 1.According to another example, a nanotip could be provided using a carbonnanotube.

[0031] A reflective holographic microscope can be provided, for example,by fitting a nanotip emitter into a scanning electron microscope (SEM)such as a Hitachi CD-SEM. Using a tungsten nanotip emitter as discussedin the Fink et al. reference, for example, an effective tip radius ofless than 3 nm can be provided, and turn on energies can be provided inthe range of 60V to 100V. The resulting emission current can be variedfrom less than 1 nA to nearly 1 μA for extraction voltages in the rangeof 60V to 500V, and a brightness of 10⁷ Amp/cm²/str. at 500 eV can beprovided. Moreover, an emission stability of less than 5% can beprovided at a pressure of 10⁻⁸ torr for over a one minute period.

[0032] According to a particular example of the present invention, arelatively low energy of less than 100 eV can be applied between theradiation source 33 and the sample surface 41 to generate the divergentbeam 34 of coherent electrons. The divergent beam 34 can thus provide anillumination footprint in the range of 20 μm to 30 μm in diameter on thesample surface. The electrons in the divergent beam 34 are elasticallyscattered at the sample surface 41 by reflection from the innerpotential of the sample, and reflected (scattered) and unreflected(unscaftered) portions of the divergent beam interfere to provide theinterferogram (Fresnel hologram) at the interference plane 36. Becausethe interference plane is provided downstream from the radiation source33, the resulting hologram can be referred to as a forward scatterhologram.

[0033] Because the resolution of an electron hologram is determined bythe wavelength of the electrons used to form the hologram, very highresolutions can be provided. In particular, a resolution on the order ofthree times the wavelength of the electrons can be provided.Accordingly, a resolution of less than one nanometer may be possibleusing an electron beam energy of 50 eV. Moreover, there may be little orno diffraction limit because the incident beam is divergent. Inaddition, lens aberrations and/or distortions can be reduced oreliminated because no lenses are required.

[0034] Radiation damage to the sample surface and charging of the samplesurface can be reduced when compared to systems such as a scanningelectron microscope. First, the damage and charging can be reducedbecause the electron beam can be generated using relatively low energiesof less than 100 eV. Second, the damage and charging can be reducedbecause the divergent beam is spread over a relatively wide area ascompared to more focused beams used in scanning electron microscopes. Anadditional potential advantage of the reflective holographic microscopeof FIG. 1 is that the hologram can be a more robust format for data thana conventional image because the resulting phase and amplitudeinformation can provide more information. Furthermore, the reflectiveholographic microscope of FIG. 1 does not require focusing, and a widerange of magnifications can be provided without significant adjustment.

[0035] While examples of reflective holographic microscopes and methodsof FIG. 1 are discussed as including a radiation source that generates adivergent beam of coherent electrons to provide an electron hologram,other sources of radiation may be used. For example, a laser can be usedto provide a divergent beam of coherent light.

[0036] As discussed above with regard to FIG. 1, reflective holographicmicroscopes and methods can be used to generate images of and/or measuredimensions of a surface feature of a sample. A reflective holographicmicroscope can thus be used for critical dimension (CD) metrology formicroelectronic processing to verify sizes and spacings ofmicroelectronic structures.

[0037] A reflective holographic microscope can also be used for defectdetection in microelectronic processing. In general, an interferencepattern generated by a defect such as a particle will be distinct withrespect to an interference pattern generated by an intendedmicroelectronic structure such as a gate electrode or a conductive line.Accordingly, a reflective holographic microscope can be used to detectdefects and provide a measure of a defect density. FIGS. 2-5 illustrateexamples of holograms produced by a particle(s) on a smooth substratewhen analyzed using a reflective holographic microscope.

[0038] In FIG. 2A, a single 5 nm sphere 45 on the surface of a siliconwafer 47 subjected to coherent electron beam 49 at 50 eV can generatethe computed hologram 51 with 100×100 pixels shown in FIG. 2B. Asdiscussed above, the hologram is an interference pattern of reflectedand unreflected components of the coherent radiation 34. The hologramgenerally is not an image, so reconstruction is needed to generate animage of the sphere. A spherical particle defect on a silicon waferwould thus produce a similar interference pattern which could be readilyidentified to determine a defect density.

[0039] In FIG. 3A, two 5nm spheres 55A and 55B are on a siliconsubstrate 57 spaced by 5 nm. The two 5 nm spheres can be subjected tocoherent electron beam 59 at 50 eV to generate the computed hologram 61shown in FIG. 3B. The extra fringes carry information that can be usedto determine the spacing and relative positions of the two spheres. Twospherical particle defects on a silicon wafer would thus produce asimilar interference pattern.

[0040] In FIG. 4A, two 5 nm spheres 65A and 65B are placed 5 nm apart,one above the other with respect to a silicon substrate 67. The two 5 nmspheres can be subjected to coherent electron beam 69 to generate thecomputed hologram 71 shown in FIG. 4B. In FIG. 5A, a 5 nm cube 75 on asilicon substrate 77 can be subjected to coherent electron beam 79 togenerate the computed hologram 81 shown in FIG. 5B. As shown in FIGS.2-5, holograms generated using a coherent electron beam can be used toidentify, characterize, and/or quantify defects on a substrate surface.

[0041] A reflective holographic microscope 91, using a laser 92 as asource of coherent radiation, is illustrated in FIG. 6. In particular, adivergent beam of coherent radiation 94 can be generated using laser 92and short focal length lens 93. Portions of the divergent beam ofcoherent radiation 94 reflect off the sample surface 101 including theraised portion 103, and reflected and unreflected portions provide aninterferogram or hologram at the interference plane 96 of the detector95. The detector 95 provides a measure of the interferogram to thecontroller 97 which can reconstruct a three-dimensional image of thesample surface. The three-dimensional image can be provided on theoutput device 99, and the laser 92 can operate responsive to thecontroller 97.

[0042]FIG. 7 illustrates a reconstructed image generated by a pointprojection microscope as discussed above. More particularly, the imageof FIG. 7 is a three dimensional reconstruction of approximately 100 nmfeatures on a SCALPEL mask performed using off-axis holography.

[0043] While reflective holographic microscopes have been discussed withrespect to coherent radiation such as coherent electron and laser beams,it will be understood that any form of coherent radiation can be used inreflective holographic microscopes.

[0044] Interference patterns can also be used to provide patterning formicroelectronic structures. Examples of systems and methods usinginterference patterns for patterning are illustrated in FIG. 8. Asshown, a patterning system 131 can be used to pattern a layer 151 of amicroelectronic structure 153. In particular, the patterning system caninclude a source of coherent radiation 133, a patterning reflectorhaving a surface 141, and a controller 137. The radiation source 133generates a divergent beam of coherent radiation 134, portions of whichare reflected off the surface 141 of the patterning reflector whereinthe surface 141 includes information that corresponds to an inverseholographic projection used to pattern the layer 151. Portions of thecoherent radiation can also be transmitted to the layer 151 withoutreflecting off the reflector surface 141 to interfere with the portionsof the coherent radiation reflected off the reflector surface.

[0045] The layer 151 to be patterned is placed in the path of reflectedand unreflected portions of the coherent radiation 134 to define aninterference plane. Accordingly, a Frenel hologram or interferogram canbe defined on the layer 151 as reflected and unreflected portions of thecoherent radiation 134 interfere at the layer 151. Portions of the layer151 can be selectively maintained and removed depending on the intensityof the hologram thereon. For example, the layer 151 can be a layer of aphotosensitive material, such as photoresist, that can be chemicallydeveloped so that portions thereof are removed or maintained dependingon the intensity of the radiation interference pattern incident thereon.The patterned photoresist can then be used as a patterning mask toselective etch an underlying layer of a device functional material.

[0046] Alternately, the patterning system 131 can be used to directlypattern a layer of a device functional material without using aphotoresist layer. For example, the layer 151 can be a layer of siliconoxide (or other device functional material) on the order of two atomsthick, and portions of the silicon oxide layer can be removed byrelatively high intensity portions of the hologram or interferogramformed thereon. The surface 141 of the patterning reflector thusdetermines the hologram or interferogram formed on the layer 151, sothat different surface patterns of the patterning reflector can be usedto define different patterns in the layer 151.

[0047] The cross-sectional view of the patterning reflector surface 141illustrated in FIG. 8 is provided by way of example with a singletopographical feature to show how the divergent beam of coherentradiation 134 can react with features of the reflector surface 141. Itwill be understood, however, that a reflector surface 141′ for thepatterning system can have numerous topographical features 141A′-D′ ofdifferent shapes as shown in FIG. 9. Moreover, the numeroustopographical features can be arranged in various patterns such as dotsand/or circles across the reflector surface.

[0048] While the reflector surfaces 141 and 141′ are shown withtopographical features being used to generate interference patterns,other characteristics of reflector surfaces can be used to generate adesired interference pattern. For example, the reflector surface may beprovided with areas of differing reflective/absorption properties; areasof differing compositional density; areas of differing electrostaticproperties; areas of differing magnetic properties; and/or areas ofdiffering topology. More generally, any variation in properties of thereflector surface that provide different reflective properties can beused to generate the interference pattern.

[0049] By way of example, an intensity distribution across a beam ofcoherent radiation projected toward the reflector surface can bearbitrarily adjusted by generating an interference pattern with abi-prism or other electrostatic or magnetic devices. The intensity andphase information in the patterning wave front will depend on theinteraction of an unreflected portion of the coherent beam transmitteddirectly from the source 133 to the layer 151 and a portion of thecoherent beam reflected off the reflector surface. The patterning wavefront at the layer 151 contains specific spatial and structuralinformation to be transformed into specific two-dimensional and/orthree-dimensional structures on the layer 151. Accordingly, thereflective surface contains sufficient information, such that when thecoherent beam reflects off the reflecting surface and interferes with anon-reflected portion of the coherent beam, an image can be patternedinto the layer 151, whether the layer 151 is a photoresist or a devicefunctional material such as, for example, silicon, an oxide, a nitride,or a metal.

[0050] The substrate surface including the layer 151 can be maintainedin the path of the reflected radiation so that the interference patternis projected onto the substrate surface including the layer. Aftermaintaining the substrate surface including the layer in the path of thereflected and non-reflected radiation, the layer can be developed sothat portions thereof are maintained and removed according to theintensity of the interference pattern thereon.

[0051] As will be understood by those having skill in the art, thecontroller can be implemented using special purpose hardware-basedsystems, general purpose computer systems together with computerinstructions, and/or combinations of special purpose and general purposesystems. As will be further understood, the controller can beimplemented using one or more integrated circuit devices, combinationsof discrete circuit devices, and/or combinations of discrete andintegrated circuit devices. The controller can also be used to maintainrelative positions of the radiation source 133, the reflector surface141, and the microelectronic structure 153.

[0052] According to a particular example of FIG. 8, the radiation source133 can project a coherent beam of electrons. For example, the radiationsource can be a field emitter that emits an electron beam in response toa voltage applied thereto. In particular, the radiation source can be ananotip field emitter wherein the tip has dimensions on the order of anatom. By providing a nanotip with these dimensions, a coherent electronbeam can be generated by applying a voltage difference between theradiation source and the reflector surface 141.

[0053] The preparation of a single-atom tip from W [111]-oriented singlecrystal wires is discussed, for example, in the reference by Hans-WernerFink et al. entitled State Of The Art Of Low-Energy Electron Holography,Electron Holography, A. Tonomura et al. (Editors), Elsevier Science B.V., 1995. The Fink et al. reference also discusses the generation of abeam of coherent electrons using the single-atom tip. The Fink et al.reference is hereby incorporated herein in its entirety by reference.The voltage difference between the radiation source 133 and the samplesurface 141 can be generated using the controller 137 as shown in FIG.8. According to another example, a nanotip could be provided using acarbon nanotube.

[0054] A relatively low energy of less than 100 eV can be appliedbetween the radiation source 133 and the sample surface 141 to generatethe divergent the divergent beam 134 of coherent electrons. Theelectrons in the divergent beam 134 are elastically scattered at thereflector surface 141 by reflection from the inner potential of thesurface, and reflected (scattered) and unreflected (unscattered)portions of the divergent beam interfere to provide the interferencepattern (such as an interferogram or Frenel hologram) at the layer 151being patterned. Because the interference pattern is generateddownstream from the radiation source 133 the resulting interferencepattern can be referred to a forward scatter hologram.

[0055] Because the resolution of an electron hologram is determined bythe wavelength of the electrons used to form the hologram, very highresolution can be provided. In particular, resolution on the order ofthee times the wavelength of the electrons can be provided. Accordingly,a resolution of less than one nanometer may be possible using anelectron beam energy of 50 eV. Moreover, there may be little or nodiffraction limit because the incident beam is divergent. In addition,lens aberrations and/or distortions can be reduced or eliminated becauseno lenses are required.

[0056] While examples of a patterning system and methods of FIG. 8 arediscussed as including a radiation source that generates a divergentbeam of coherent electrons to provide an electron hologram, othersources of radiation may be used. For example, a laser can be used toprovide a divergent beam of coherent light. According to this example,the radiation source might include a laser and a short focal length lensto provide a divergent beam of coherent radiation.

[0057] Patterning using interference patterns as discussed above mayprovide tolerance to defects on the reflecting surface 141. Defects inthe reflecting surface 141 are expected to exhibit structures andsignatures in Fourier space different than the structures and signaturesof the intended pattern. These defect signatures can thus be separatedand/or filtered in Fourier space. Moreover, any defect information maybe convolved with the entire set of phase and amplitude information thatimpinges on the imaged layer 151. Accordingly, defect information may bediluted across the imaged surface. Accordingly, in the transformationfrom reflector information to imaged information, small defects on thereflector surface 141 may not print on the layer 151. Methods andsystems according to embodiments of the present invention can thusprovide defect tolerant patterning for microelectronic structures withrelatively fine dimensions.

[0058] A controller 137 can be used to control the duration andintensity of the coherent radiation 134. The controller can also be usedto maintain relative positions of the radiation source 133, thereflector surface 141, and the microelectronic structure 153. Asdiscussed above with regard to the microscope of FIGS. 1 and 6, theradiation source 133 can be an electron emitter, a laser, or source ofother coherent radiation.

[0059] Alternate reflective patterning methods and systems 331 areillustrated in FIG. 10 including a reflector surface 341, a plurality ofradiation sources 333A-B, and a controller 337 used to pattern layer 351of substrate 353. As shown, the reflective patterning system 331 mayinclude a plurality of radiation sources 333A-B to generate acorresponding plurality of beams of coherent radiation 334A-B. Portionsof each of the beams of coherent radiation are transmitted directly tothe layer 351 to be patterned, and portions of the beams are reflectedoff the reflector surface 341 to the layer 351. With a plurality ofradiation sources, each radiation source can be used to transmitdifferent information to pattern the layer 351, and/or the intensity ofthe interference pattern(s) at the layer 351 can be increased toincrease throughput.

[0060] Additional reflective patterning methods and systems 441 areillustrated in FIG. 11 including a plurality of reflector surfaces441A-B, a plurality of radiation sources 433A-B, and a controller 437used to pattern layer 451 of substrate 453. As shown, the reflectivepatterning system 431 may include a plurality of radiation sources433A-B to generate a corresponding plurality of beams of coherentradiation 434A-B. Portions of each of the beams of coherent radiationare transmitted directly to the layer 451 to be patterned, and portionsof the beams are reflected off the respective reflector surfaces 441A-Bto the layer 451. With a plurality of radiation sources and reflectors,each combination of radiation source and reflector can be used totransmit different information to pattern the layer 451, and/or theintensity of the interference pattern(s) at the layer 451 can beincreased to increase throughput.

[0061] Yet other reflective patterning methods and systems 541 areillustrated in FIG. 11 including a reflector surface 541, a radiationsource 533A-B, a filter 555, and a controller 537 used to pattern layer551 of substrate 553. As shown, the reflective patterning system 531 mayinclude a radiation source 533 to generate a beam of coherent radiation534. Portions of the beam of coherent radiation are transmitted directlyto the layer 451 to be patterned, and portions of the beam are reflectedoff the reflector surface 541 to the layer 551. More particularly,portions of the beam reflected off the reflector surface 541 to thelayer 551 can be transmitted though filter 555 to reduce the generationof defects in the layer 551 being patterned resulting from defects inthe reflector surface 541.

[0062] As discussed above, defects in the reflector surface can beexpected to have structures and signatures in Fourier space differentthan those of the desired patterns in the reflector surface.Accordingly, the filter 555 can separate and/or filter defect signaturesin reflected portions of the beam to reduce resulting defects in thelayer being patterned. The filter, for example, can be an electrostaticor electromagnetic filter that shapes the reflected portions of anelectron beam to reduce defect signatures. If the radiation beam is anoptical beam, the filter can be an optical lens. Moreover, filters canbe used in patterning systems including multiple radiation sourcesand/or reflector surfaces. The system of FIG. 10, for example, couldinclude one or more such filters to filter radiation reflected from thereflector surface toward the layer 351. The system of FIG. 11 couldinclude one or more filters between each of the reflector surfaces andthe layer 451.

[0063] In addition, the patterning methods and systems of FIGS. 8, 10,11 and 12 may be configured to accept different reflectors to allowpatterning of different layers and/or devices. In other words, a firstreflector(s) could be used to pattern on first layer of a device and asecond reflector(s) could be used to pattern a second layer of the samedevice. Alternatively, a first reflector(s) could be used to pattern afirst layer of a first device, and a second reflector(s) could be usedto pattern a second layer of a second device.

[0064] In the drawings and specification, there have been disclosedtypical preferred embodiments of the invention and, although specificterms are employed, they are used in a generic and descriptive senseonly and not for purposes of limitation, the scope of the inventionbeing set forth in the following claims.

That which is claimed is:
 1. A method for patterning a layer on asubstrate, the method comprising the steps of: projecting coherentradiation toward a reflector surface so that the coherent radiation isreflected off the reflector surface to provide a holographic projectionof a desired image wherein the reflector surface includes informationthat corresponds to an inverse of the holographic projection of thedesired image; and maintaining the substrate including the layer in thepath of the of the reflected radiation so that the holographicprojection is projected onto the layer.
 2. A method according to claim 1further comprising the step of: developing the layer so that portionsthereof are maintained and removed according to the intensity of theholographic projection of the desired image thereon.
 3. A methodaccording to claim 1 wherein the layer comprises an oxide layer that isactivated on exposure to portions of the holographic projection of thedesired image having sufficient intensity, so that activated portions ofthe oxide layer can be selectively removed, maintained, or modified. 4.A method according to claim 1 wherein the layer comprises a siliconlayer that is activated on exposure to portions of the holographicprojection of the desired image having sufficient intensity, so thatactivated portions of the silicon layer can be selectively oxidized ormodified.
 5. A method according to claim 1 wherein the step ofprojecting coherent radiation comprises projecting a coherent beam ofelectrons.
 6. A method according to claim 5 wherein the step ofprojecting coherent radiation further comprises generating the coherentbeam of electrons from a nanotip field emitter.
 7. A method according toclaim 6 wherein the nanotip field emitter comprises a tip havingdimensions on the order of an atom.
 8. A method according to claim 1wherein the step of projecting coherent radiation comprises projectinglaser radiation.
 9. A method according to claim 1 wherein theholographic projection of the desired image comprises a Fresnelhologram.
 10. A method according to claim 1 wherein the step ofprojecting the coherent radiation comprises projecting the coherentradiation along divergent paths.
 11. A method according to claim 1further comprising: filtering the coherent radiation reflected off thereflector surface to reduce transmission of portions of the interferencepattern corresponding to defects on the reflector surface.
 12. A methodaccording to claim 1 wherein projecting coherent radiation comprisesprojecting two beams of coherent radiation toward the reflector surface.13. A method according to claim 1 further comprising: projectingcoherent radiation toward a second reflector surface so that thecoherent radiation is reflected off the second reflector surface toprovide a second holographic projection of reflected radiation; whereinmaintaining the substrate further comprises maintaining the substrateincluding the layer in the path of the radiation reflected off thesecond reflector surface so that the second holographic projection isprojected onto the layer.
 14. A method according to claim 1 furthercomprising: projecting a portion of the coherent radiation to the layerwithout reflecting off the reflector surface.
 15. A system forpatterning a layer on a substrate, the system comprising: means forprojecting coherent radiation toward a reflector surface so that thecoherent radiation is reflected off the reflector surface to provide aholographic projection of a desired image wherein the reflector surfaceincludes information that corresponds to an inverse of the holographicprojection of the desired image; and means for maintaining the substrateincluding the layer in the path of the of the reflected radiation sothat the holographic projection of the desired image is projected ontothe layer.
 16. A system according to claim 15 wherein the layercomprises an oxide layer that is activated on exposure to portions ofthe holographic projection of the desired image having sufficientintensity, so that activated portions of the oxide layer can beselectively removed, maintained, or modified.
 17. A system according toclaim 15 wherein the layer comprises a silicon layer that is activatedon exposure to portions of the holographic projection of the desiredimage having sufficient intensity, so that activated portions of thesilicon layer can be selectively oxidized or modified.
 18. A systemaccording to claim 15 wherein the means for projecting coherentradiation comprises means for projecting a coherent beam of electrons.19. A system according to claim 18 wherein the means for projectingcoherent radiation further comprises means for generating the coherentbeam of electrons from a nanotip field emitter.
 20. A system accordingto claim 19 wherein the nanotip field emitter comprises a tip havingdimensions on the order of an atom.
 21. A system according to claim 15wherein the means for projecting coherent radiation comprises means forprojecting laser radiation
 22. A system according to claim 15 whereinthe holographic projection of the desired image comprises a Fresnelhologram.
 23. A system according to claim 15 wherein the means forprojecting the coherent radiation comprises means for projecting thecoherent radiation along divergent paths.
 24. A system according toclaim 15 further comprising: means for filtering the coherent radiationreflected off the reflector surface to reduce transmission of portionsof the interference pattern corresponding to defects on the reflectorsurface.
 25. A system according to claim 15 wherein the means forprojecting coherent radiation comprises means for projecting two beamsof coherent radiation toward the reflector surface.
 26. A systemaccording to claim 15 further comprising: means for projecting coherentradiation toward a second reflector surface so that the coherentradiation is reflected off the second reflector surface to provide asecond holographic projection of reflected radiation; and means formaintaining the substrate including the layer in the path of theradiation reflected off the second reflector surface so that the secondholographic projection is projected onto the layer.
 27. A systemaccording to claim 15 further comprising: means for projecting a portionof the coherent radiation to the substrate including the layer withoutreflecting off the reflector surface.
 28. A system for patterning alayer on a substrate surface, the system comprising: a radiation sourcethat is configured to project coherent radiation toward a reflectorsurface so that the coherent radiation is reflected off the reflectorsurface to project a holographic projection of a desired image on thelayer so that the holographic image of the desired image is used topattern the layer.
 29. A system according to claim 28 wherein the layercomprises an oxide layer that is activated on exposure to portions ofthe holographic projection of the desired image having sufficientintensity, so that activated portions of the oxide layer can be removed,maintained, or modified.
 30. A system according to claim 28 wherein thelayer comprises a silicon layer that is activated on exposure toportions of the holographic projection of the desired image havingsufficient intensity, so that activated portions of the silicon layercan be selectively oxidized or modified.
 31. A system according to claim28 wherein the coherent radiation comprises a coherent beam ofelectrons.
 32. A system according to claim 31 wherein the radiationsource comprises a nanotip field emitter.
 33. A system according toclaim 32 wherein the nanotip field emitter comprises a tip havingdimensions on the order of an atom.
 34. A system according to claim 28wherein the coherent radiation comprises laser radiation.
 35. A systemaccording to claim 28 wherein the holographic projection of the desiredimage comprises a Fresnel hologram.
 36. A system according to claim 28wherein the radiation source projects the coherent radiation alongdivergent paths.
 37. A system according to claim 28 further comprising:a filter that is configured to filter the coherent radiation reflectedoff the reflector surface to reduce transmission of portions of theinterference pattern corresponding to defects on the reflector surface.38. A system according to claim 28 wherein the radiation sourcecomprises two radiation sources that are each configured to project arespective beam of coherent radiation toward the reflector surface. 39.A system according to claim 28 wherein the radiation source is furtherconfigured to project coherent radiation toward a second reflectorsurface so that the coherent radiation is reflected off the secondreflector surface to project a second holographic projection ofreflected radiation on the layer.
 40. A system according to claim 28wherein the radiation source projects a portion of the coherentradiation to the layer without reflecting off the reflector surface.